Continuously variable transmissions, having an input and an output shaft and a variator consisting of at least two toroidal discs with toroidal races between which rolling bodies run on, are to be understood as being known from the literature in multiple embodiments.
DE-A 28 07 971 shows a simply designed toroidal drive having one input and one output shaft and two discs which accommodate between them rolling bodies. The rolling bodies are mounted in supports and can be tilted via an axially movable drum. In this manner the reduction ratio is changed.
Examples of continuously variable transmissions having two power ranges or operation systems are known from European patents 0 043 184 and 0 078 124. In the transmission of EP-A 0 078 124, the input power is conveyed in a first ratio range, via a wave train and a variator, to a summarizing transmission in the form of a planetary gear. Depending on the prevalent speed ratios, the transmission is in a geared neutral state or reduction ratios of the whole transmission are produced for reverse and low forward speeds. In a second ratio range, the input power is directly transmitted via a variator to the output shaft. This transmission has the disadvantage that the variator is operated with power distribution in the first power range so that the total effectiveness deteriorates.